Effect of transfer ribonucleic acid dimer formation on polyphenylalanine biosynthesis

Escherichia coli tRNAPhe (anticodon GAA) as well as yeast tRNAPhe (anticodon GmAA) forms a strong complex with E. coli tRNAGlu (anticodon s2UUC) through an interaction between their complementary anticodons. This interaction inhibits aminocylation of tRNAPhe but not the formation of a complex with elongation factor Tu. Moreover, at 0 degrees C, tRNAGlu strongly inhibits the binding of Phe-tRNA to poly(U)-programmed ribosomes via either the enzymic (EF-Tu-promoted) or nonenzymic pathway. At 15 degrees C, tRNAGlu effectively inhibits polyphenylanine synthesis in the E. coli system. The inhibition is reversed at 37 degrees C, where the Phe-tRNA.tRNAGlu dimer is dissociated. Calculations based upon the E. coli intracellular concentrations of tRNAs and the published rates of association and dissociation of the tRNA dimers suggest that this interaction may inhibit protein synthesis in vivo at temperatures below 15 degrees C.